1. Background of the Invention
This invention relates to material conveyor systems and more particular to material conveyor systems that utilize free roaming apparatus for application in a work area such as a factory and still more particular to material conveyor systems that utilize television cameras as a means of tracking and guiding the free roaming mobile apparatus and still more particular to a reflection filter for use in the material conveyor system.
The problem with false readings due to reflections has been widely discussed in articles that relate to radar, seismic, sonar, and other temporal technologies. For the spatial reflection problem, such as that encountered in astronomy, however, no general solution has been found. In the prior art of machine vision, reflections have been controlled by using optical techniques such as blinders and by eliminating reflective surfaces from the viewing area. Careful control of the viewing area and the visual environment including the control of the ambient illumination has been a recurring characteristic of most machine vision art. However, in a manufacturing environment which must be occupied not only with machines but with humans, such control is difficult or impossible. Lighting is designed to meet the human requirements first and the placement of surfaces, walls and windows in dictated by functionality, building regulations and other constraints.
2. Summary of the Invention
A visual navigation system that rejects reflected images navigates an electrical controllable apparatus such as a mobile robot. The mobile robot is fitted with a minimum of three navigation beacons with emit a light visible to overhead television cameras. The beacons are arranged so as to form a triangle. The shape and the dimension of the triangular patterns are measured and stored in a memory unit within the visual navigation system and when a reflected image is received it will be a different type of angle and thus the vision navigation system is able to distinguish the reflected image from the primary image of the mobile robot.
The mobile apparatus includes a plurality of light sources or beacons arranged in a triangular pattern in the form of a right-handed asymmetrical triangle. Automatic classification of an image as to a right-handed or a left-handed triangle includes the following steps of identifying the hypotenuse chord, determining the perimeter and a first direction such as clockwise and if the chords are traversed in ascending order, then the triangle is right-handed. If the chords are traversed in a descending order, then the triangle is left-handed. Since it is known that the image will appear as right-handed, then any left-handed triangle image must be due to a mirror image transformation and is thus a reflected triangle and can be discarded by the visual navigation system.
It is the object of this invention to provide a visual navigation system for a mobile robot that is impervious to interference caused by reflected images.
It is another object of the invention to provide a visual navigation system in which a mobile robot has three navigational beacons and the visual navigation systems can distinguish from the reflection of one beacon, two beacons, or more beacons due to partial reflections of the primary image of the mobile robot.
These objects and advantages will become more apparent from from the reading of the specification in conjunction with the figures in which: